


Heatwave

by kuchi



Series: Heartlines [4]
Category: Avatar: The Last Airbender
Genre: F/M, Inappropriate Use of Bending (Avatar), M/M, Multi, Plot What Plot/Porn Without Plot, Porn with Feelings, Reunion Sex, Threesome
Language: English
Status: Completed
Published: 2020-04-19
Updated: 2020-04-19
Packaged: 2021-03-01 04:48:02
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,163
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23249485
Author URL: https://archiveofourown.org/users/kuchi/pseuds/kuchi
Summary: "Zuko," Aang pants, watching Katara with cloudy eyes, betraying what looks puzzlingly like a hint of apprehension. "D–do what we did before."
Relationships: Aang/Katara (Avatar), Aang/Katara/Zuko (Avatar), Aang/Zuko (Avatar), Katara/Zuko (Avatar)
Series: Heartlines [4]
Series URL: https://archiveofourown.org/series/1364209
Comments: 47
Kudos: 442
Collections: Smut 4 Smut 2020





	Heatwave

**Author's Note:**

  * For [Rubynye](https://archiveofourown.org/users/Rubynye/gifts).



> I can't believe i get to write my fav ot3 for an exchange! hope you like it rubynye!!

Aang shifts in his seat for the hundredth time, letting out a sigh that inadvertently sends half the scrolls in front of him careening off the edge of the desk. Across from him, the Chairman of the Fire Nation High Council is tirelessly reciting page fifteen out of twenty-one of the protocol for tomorrow's official ceremony for the Avatar's two-week cross-country tour of the nation's updated industrial centres. He's a nice guy, really – better company than most of Zuko's overly stiff entourage – but the sooner this meeting ends, the sooner Aang can get out of here, take his well-worn shortcut through the inner courtyard, and get to the Fire Lord's private wing.

Katara's probably already there, and Zuko probably isn't. The last leg of her latest project – getting medics in all four nations to be able to collaborate on their knowledge in yearly conferences – brought her to the Fire Nation weeks ago. Aang can't help but be jealous of the lengthy time they've been spending together while he's been stuck in Republic City for months, stuck mediating land disputes due a series of disturbances that were bound to take place sooner or later as more and more people from all over migrate there.

It's not uncommon for either of them to be able to catch up with Zuko in Republic City, but getting three people in one place is harder than two, and getting three people somewhere decidedly _private_ is almost unheard of in the hubbub of the ever-growing city.

Katara's last letter hadn't helped in that regard at _all_. The things she implied they'd been getting up to made blood rush to the tips of Aang's ears. He would have dropped every meeting for a chance to see the effect they would have on Zuko. But as far as bedroom activities go, he has something more pressing to tell Katara. The last time he and Zuko had been alone together in Republic City had been rather... enlightening.

To be totally honest, it makes him break a sweat to think about telling Katara. And break a sweat in general. But it doesn't feel right that she _doesn't_ know, and the particulars of the… incident make him feel strange and guilty. It would be nice to have Zuko here, to help him explain. They could handle Katara between them. Maybe.

The thought only ratchets his impatience. He settles himself and nods importantly to the Chairman.

*

" _Yeah, yeah, you feel good, you feel good, you're amaz–aghghhh," Aang's saying, all barely coherent._

_Zuko marvels at the sheer energy he exudes, even while he's pressed haphazardly between Zuko, and, well, Zuko's desk. It's always a challenge, getting Aang to shut up, to turn his very unnecessary words to mush. But Zuko's never been one to back away from a challenge, and the payoff is exhilarating. He grunts, hitching up Aang's sprawling legs higher against his sides, and angles to kiss the long hollow of his throat._

_Aang shudders wholeheartedly in response. "You–" he says to the sky-high ceiling, "you're awesome, you're awesome–ah."_

_Zuko's chest blooms at those words, his face hot with satisfaction even if part of him wants to snap at Aang, wants to deny it. He channels the unease into the thrust of his hips, garnering another strangled sigh from Aang, who yanks himself up and reaches to get a handful of Zuko's hair. Zuko pushes him down with more than a little force. Despite how good that grip feels, he doesn't want anything right now except to make Aang pliant for him._

_Aang rises again – Zuko's mind is too hazy, too narrowed with lust to perceive if there's any airbending involved in that – and grips his hair hard again at the base of his head. Zuko is struck by a strange deja vu; it's like sparring. Just as well, he should have figured there was no chance for an easy victory._

" _You're going to kill me,'' Aang mutters under a groan, eyes gentle enough to make Zuko's stomach drop._

_Something hot and quick flares up between them._

_Aang bolts upright on the desk, eyes flashing._

_Zuko gasps, at a loss for words. That... should not be happening. His own heartbeat thunders in his ears. It's the most basic fire training, controlling wayward bursts of emotion. He should have mastered it decades ago._

_Though he's never been exposed to a sight like this before. "I– I'm so sorry, Aang– I didn't think it w–"_

_Aang's shaking his head inelegantly into Zuko's chest before he can finish._

_A maddening silence grows between them, Zuko's head throbbing with guilt, until Aang lifts his head and Zuko can see his eyes. They're wide open. Open – not recoiling, not alarmed, not scared._

" _Zuko," he rasps, head tipping forward again until his chin rests over Zuko's shoulder. "It's fine." Zuko can feel Aang's pulse rioting against his neck, his slippery hands grasping at Zuko's shoulder blades. "It's... more than fine."_

_Before Zuko can lean away, confused, Aang mutters in his ear, "Do you think you could do that again?"_

_Zuko almost loses his footing. "Are you crazy?"_

_Aang grinds into him, distractingly persistent movements that betray his arousal. His eyes, however, are dead sober. "No," he says emphatically._

_Zuko grabs his shoulders, holding him still. "What – why? Do you really want this?" He shivers at how far gone Aang must be, to even ask about something like that. He's not afraid of using firebending – no master firebender could be – but no sane person would ask for this so carelessly. Not unless they were literally, truly turned on by it._

_Aang slips away from his sweaty grip. "Yeah," he says, eyes glinting a little recklessly._

_With his head reeling, Zuko cautiously conjures up a flame between them, begrudging the way he needs to clear his mind and concentrate for it to materialise this time. Stupid Aang. They could very well just continue on like rabaroos, instead he's asking Zuko for something that actually requires technique and concentration._

_He's about to crack a joke about how the tables have turned with their unplanned firebending practice but the thought falters as he notices Aang's eyes watching the flame. A minute flicker of fear, a hitch in the heartbeat pressed against Zuko on too many focal points to not be distracting. Zuko lets the flame disperse, licking the air close to Aang's heaving chest._

_He tries to blink away the feeling that this isn't right. Aang shouldn't want to be held to fire, that's just entirely messed up. And Zuko should know better than to indulge him, he shouldn't be gaining some animal pleasure from subjecting him to it, like a mockery of the destruction he knows he's capable of. They've both been scarred by fire in more ways than one._

" _Aren't you scared?"_

_Aang's voice is deathly quiet. "It's just you," he says, as if that's the entire explanation._

_Zuko swallows.  
_

_If Aang trusts him, that's what compels Zuko to prove him right._

_Another curl of warmth spreads from his hands, lingering close to Aang's arms. Slowly, it dances itself into a ring of fire circling his shoulders. It takes an absurd amount of focus to suspend fire in action, to keep the tightrope distance from Aang's skin that makes it just dangerous enough to be exciting._

_A desperate moan breaks out of Aang, pained with the nigh-impossible task of keeping still. Zuko concedes that's a little funny. The look in his eyes, too, is a molten reflection of Zuko's flames. It's strange how perfectly still Aang can sit while giving the impression of jumping out of his skin. Zuko traces his hand in a line down Aang's torso, and tiny flames flutter to race behind it. When the warmth seeps low enough on Aang's stomach he's rewarded with a protracted sigh._

_Heat stings Zuko's eyes._

_There's something ridiculous about this whole affair. He could really hurt Aang with this if he had any desire to. And Aang could have him flatter than the desk beneath them if he wanted, Avatar powers and all. But instead he's letting Zuko do this._

_Aang tips his head back, resting his weight on the desk. Unthinkingly, Zuko bends to kiss the tip of his ear, brazenly licking the sweat trickling down his temple as he sits rigid and ready for whatever Zuko wants to do with him. After a few more electrifying moments of heat, Aang slips his arm between their bodies and swiftly sucks the air out between them, smothering the fire._

" _Zuko," he mutters, foggy. Zuko pushes him back down in response._

" _Zuko?"_

"Zuko!"

"What?" he snaps, shaken abruptly out of the memory. He whirls around. He's in his private quarters – thank _every_ Spirit – and Katara, Katara's here. She tilts her head quizzically, her arms stretched around a huge pile of scrolls which she unceremoniously drops onto his desk. Oh. Desks.

Katara raises an eyebrow. "Don't tell me you're overworking yourself again." She runs a hand sweetly across his hairline that has the exact opposite effect to what she had probably intended. "Aang's here already. One of the guards told me. We'll probably see him at dinner, let's go!"

Zuko scrambles for his bearings and returns her sunny smile. "That's great. I'm– uh. You go ahead. I'm going to use the bathroom."

*

Katara sweeps her hands down Aang's shoulders before resting her head on his chest. She sighs, content. The Fire Nation never gets truly cold, but there's a blissful breeze billowing in from Zuko's balcony. She leans up to draw Aang into a slow kiss firmly intended to mark the end of their current time apart.

He returns the kiss, and then some. She laughs at his eagerness, trailing her hands down his bare back as he's kissing down her chest, all the way to her very bare stomach, a motion that makes her toes curl into the silky-soft royal bedding. Fire Nation street fashion has its charms.

Her breathing harshens when Aang brazenly channels the draught across her skirt, teasing up the hem of the fabric, hovering in a tantalisingly cool contrast to the heat building between her legs. Katara cups his head and shivers off the sensation, peering around the room. "Zuko? Come to bed."

Zuko is there within seconds. He lays down next to her. He has that gentle, dazed look in his eyes that he sometimes gets watching them. Katara cups his cheek and pulls him in for a long, greeting kiss. By the time Aang gets under her skirt, licking in earnest, she's feeding her shaking moans to Zuko's mouth. The two of them so temptingly near, together, is a luxury she's missed for months. She shoves Aang away with her trembling legs before he can bring her too close, guiding him back up to Zuko, watching with a gratifying spike of desire as Aang kisses him hungrily.

It's really been too long. She finds herself watching them ravenously, reaching for a moment to loosen Zuko's hair out of its knot. When Aang retreats to remove his ceremonial robes and put them away safely over one of the embroidered chairs next to the balcony, Katara takes her chance on Zuko, pushing him down into the mattress. He's already hard under her, and she's helpless to it, scrambling to get her skirt out of the way, pulling it up in bunches. She sinks down onto him carefully with the last of her patience, but she's already boneless, dazed from Aang's attention, and Zuko has to grab her hips and keep her upright with strong hands. Happy to let him control the movement, she runs her hands down his chest, stopping a moment to cover the ragged lightning scar, marvelling still at how intimately Zuko lets her touch him.

She doesn't last long with the way he grinds up into her, slow but unyielding, and by the time Aang returns she's slumped in Zuko's lap, gasping.

"I was gone for a minute," Aang says, voice light enough to disguise the raw hunger Katara can still detect in his eyes. "You animals."

Katara giggles helplessly. Zuko squirms under her and she returns her attention to him, kissing him to placate him momentarily.

He's only getting started, judging by the force of his kiss, the insistent press of his hands against her ribs, cupping her breasts. She's got an idea. Pulling away, she asks, "Hey, have _you two_ ever… you know?"

"What?" Zuko releases her from the embrace so she can look down into his face.

"You know… had sex."

Zuko appears utterly confused. When she turns, Aang's look says it all. They've been doing this for a while, the three of them.

Katara huffs. "Penetration," she says.

Zuko grows hot under her, predictably. "Once," he says, lowering his eyes from hers, already looking to Aang for elaboration.

"Yeah. Last time we were in Republic City together…" Aang trails off, staring at Zuko. There's something unsaid in the look of alarm that passes between the two of them, but Katara brushes it off, craving the more pressing details.

"And?"

Aang scratches the back of his head, coming to sit closer to them. "It was just – well I just had Zuko… penetrate… me, that's all." She winces at her initial choice of wording.

Zuko barks a laugh. "You had a lot more than that."

Relishing Aang's reddening face, she pries off Zuko and sits next to him instead. "Show me."

"R–right now?" Aang asks, his voice an octave higher.

Katara nods, tucking her hair back innocuously. "Why not? Are you feeling shy?"

"Not at all," Aang says immediately, petulant. "I'm happy to do it if Zuko is."

"Hmm…" Katara cups her hand over the evidence, making Zuko jump. "You know, I think he is."

Zuko stares with mock incredulity between the two of them. "It's pretty presumptuous for both of you to be making executive decisions in the Fire Nation without me," he says.

Katara smirks. "Are you saying you'd rather not?"

"I want to," he says, swallowing, before turning directly to Aang. "I just want you to know exactly what kind of show you're getting into."

No matter what he had said before, Aang appears to quail a little at this. It makes sense to Katara that he might be nervous about doing it in front of her – he's never done anything like that between the two of them – so she rubs a soothing hand over his chest, leaning to kiss him. "I really want to see it. Please?"

Aang laughs, nervous, running a hand along her bare shoulder and through the length of her hair. "I said I would, didn't I?"

It all happens quickly from there. Katara sits transfixed as Aang follows Zuko's instructions, procuring a small vial of oil from his dresser. It makes her heart flutter how Zuko warms it up before the trickling liquid is all over Aang's hand and eventually, between them, as Aang sits over Zuko's lap, right where she had been. It takes a few moments' worth of easing and fumbling – that Katara spends alternately soothing and kissing Aang and watching with wonder how kind, how decisive, how careful Zuko is with him.

By the time they find a rhythm, Katara's head is swimming. She pries herself away from the crook of Aang's neck, letting Zuko take her place, and settles back into the bed. Aang tips his head back, showing off ropy muscle. Neither of them are shy about being heard, she notices, and she only lasts through a couple more of Aang's heady moans before they propel her forward again.

"Stop," Katara breathes. She addresses Aang, "turn around, so I can–" she cuts herself off with a fervent nod, licking her dry lips. "So I can help you."

They do what she asks as quickly as if it's an unspoken rule. When Aang shifts to kneel facing her, Katara's attention is drawn briefly to their matching scars, Aang's back against Zuko's torso. With hardly any momentum lost, Aang stoops to kiss her, bucking into her hand at the pace of Zuko's thrusts. Katara kisses away his delirious moans, deliberately slowing her hands to provoke a reaction. Zuko, too, is far gone, muffling himself against Aang's neck, mouth on the checkpoint of his tattoo.

"Zuko," Aang pants, watching Katara with cloudy eyes, betraying what looks puzzlingly like a hint of apprehension. "D–do what we did before."

Her curiosity instantly piqued, Katara stills her movements, earning a frustrated sigh from Aang. Zuko thrusts harder, seemingly determined to ignore him.

"Zuko," he whines again, pushing back against him to get him to listen.

Zuko slows shakily. "Really?" he grunts, "now?" Even _he_ sounds hesitant.

"What?" Katara tries for nonchalance.

Aang doesn't meet her eyes. "It's nothing crazy," he says. Katara's stomach twists at how raspy he sounds, how desperate, still trying to rub up against her stomach now that she's stilled her hands. "I just– I want– it's nothing–" It's clear to her that he's feigning guilelessness, wrapping a hand around Katara's wrist before turning his head. "Come _on_ , Zuko."

Zuko shakes him a little by the arms. "It _is_ ," he says. "Be serious, Aang. It's dangerous, she should know before you spring it on her."

"Know _what_?" Katara demands, a volatile jumble of arousal and irritation making her voice rise. "Zuko?"

At least he's willing to talk to her on her level. Their eyes meet across Aang's slack frame, and Zuko's are alight with an intensity that sends Katara's blood rushing.

"That he likes," Zuko starts, and then he pulls Aang's body straight, Katara's eyes following him like prey. "That he likes _this_." He tips Aang's head back on to his shoulder with one hand, hovering the other across his throat as a blazing line of flames spring up from it, flickering close to Aang's skin.

Katara jolts back in surprise.

She hopes that Zuko is smart enough to know that attacking Aang with fire is pretty high up there on the list of things that would get someone, at the very _least_ , severely injured by her. He's successfully avoided incurring her wrath in that particular manner for many years now.

But one look into Zuko's eyes banishes that thought. Katara barely holds a gasp. He knows exactly what he's doing. Any hesitation, any fear in his eyes, diminishes the longer they look into hers – it's _because_ of her.

As it should be.

Aang moans lowly, eyes shut and shoulders taut. While part of her is still struggling to believe it, it's clear he's engaging Zuko in something completely on his own request. Aang opens his eyes, fixing on her face with wild, wide pupils. When he tries to shift forward, Zuko drops his stance by an inch, enough to let the flames encroach on his chest and prevent the movement.

Aang shakes his head and swallows down another hoarse moan. His eyes flutter open and closed, the hand around her wrist squeezing insistently.

She takes a deep breath. Okay, they're all master benders here. Terrifying as it is, it's hard not to lean into the jumpy thrill of seeing Aang's eyes darken over being held captive like this.

"And look," he says, extracting his hand from hers. "I can put it out if I want to, easy." He sweeps his hand under Zuko's, wiping out the flame.

Katara releases a long-held breath and nods. Now that the shock of the actual thing is out of the way, her mind reels at the introduction, at the _nerve_ of him, to try to jump something like that on her. She takes his hands, grasping his wrists and pinning them in front of her with all her strength. She catches Zuko's eye with a smirk. He conjures up the flame again.

Katara looks through her lashes at Aang. "Can you put it out now?"

Aang releases a guttural groan. He's babbling, "I knew you wouldn't mind, you're scarier than any fire–" he turns to Zuko, "–now finally, show me some firebending, O celebrated Fire Lord–"

Zuko chokes back a kind of laugh that makes Katara's heart catch in her throat, wrapping his arm around Aang's waist. "You are so annoying."

Katara resumes touching Aang, her wandering hands helping to keep him still since she definitely doesn't trust him to do it himself in this frenzied state. Zuko can't exactly move much while he's got flames flickering an inch from Aang's heart, but Katara can certainly stroke him senseless. She watches Zuko tenderly kiss Aang's neck while holding flames to his throat, mesmerised for who knows how long, until suddenly she notices her eyes prick.

The warmth gathering between them has reached her body, making her long hair stick to her shoulders, but it's not the fire – not literally.

She gets it, a little. Aang has been wary of firebending since they met, and especially ever since the time he burned her by accident when they were kids. Even after he got good enough to be a master, there's always been a latent distrust. Katara is the last person who can blame him. And yet –

This is safe.

Zuko is safe.

The realisation, the loose, soft expression in Aang's eyes that triggers it even as his body is rigid, it all spills into a wave of urgency in Katara's mind. She's suddenly starkly jealous of how close they are right now, of the way Aang looks blissed out with Zuko inside of him, pressed together like they belong. She slips a hand between her legs, grinding her palm up to gauge her need, but it's not enough.

She returns Aang's attention to her face by grabbing his chin firmly. "Lay down on your side," she says. Then to Zuko, "but don't stop."

She wrings off the rest of her clothing with shaking hands and lays down on the bed, beckoning Aang to face her, holding his face still in her hands and kissing the strangled sighs from his mouth when Zuko settles behind and presses into him again. Aang buries his face into her neck, and she hitches her leg up over both of them, lining their hips up and pushing the length of him into her, greedily.

Almost instantaneously, Aang groans, heaving her thigh up against his hip with a warm, wide hand and thrusting into her jerkily. His entire body trembles against her and he's mumbling, all shaky and jumbled, "Katara– I– you– it's so much, it's so much, it's too much–" The keenness of his movements – of _Zuko's_ – makes her dig her nails into his shoulder, and if that's how she feels, she can barely begin to imagine what it must be like for him.

They finish in a muddle of limbs and hands and shaky breaths. Katara can only watch Aang, mesmerised by the sheer pleasure on his face, his posture unravelling as he slumps onto his face between them. Behind him, Zuko does pretty much the same. Katara whispers a request into Aang's ear to draw out the breeze, tracing her hand down his long back, and the interruption of the scar, just as she'd done with Zuko earlier.

"I think that I should always be in the middle," Aang says once they're sufficiently cooled down, a rumbling sleepiness in his voice that satisfies Katara immensely. "Cause then neither of you has to get a mouthful of hair."

"How considerate," Katara murmurs, eyes closed. She and Zuko laugh it out, deliberately long. It's nice to ease the air – not just the evident intensity of what they did for Aang, but the firebending before, too.

"By the way, Zuko," Aang continues with a yawn. "You _need_ to try that. Avatar State has nothing on it."

Katara snorts. "I'll bet." She nuzzles her head into his chest, delighted. Her eyes flutter closed, pleasantly tired.

"Are you really okay with the fire stuff?"

For a moment, she isn't sure who speaks, exhausted and on the brink of sleep. But the familiar pace of Aang's breathing says he's already out.

She doesn't think she'll ever understand this, specifically. Fire is extrinsic. It doesn't have to obey the bender the way other elements do, even one as talented as Zuko. And so the needless recklessness of the act is a little bit beyond her. But she understands enough. It would be hypocritical not to, with the way she's deliberately misused her bending before.

"It's okay," she tells Zuko with a sleepy laugh.

"We don't have to do it that often, if you don't want to be there, I get–"

"I think I'd prefer it if I am there," Katara interrupts, taking his hand lightly over Aang's sleeping body. "I can heal. Just in case."

Zuko is roused immediately. "You'd _never_ need to–"

"I know." She smiles. "I know."

That's not the _only_ reason, but it's the only one she's willing to admit for now. She falls asleep with her hand clasped in his.

**Works inspired by this one:**

  * [Fast and Free, Then It's Quiet Again](https://archiveofourown.org/works/24006637) by [spfuzz](https://archiveofourown.org/users/spfuzz/pseuds/spfuzz)




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